Incilius alvarius
Silhouette: Jose Carlos Arenas-Monroy · PhyloPic
In 3 days ~20% in a week ~40%
The Colorado River toad (Incilius alvarius), (previously Bufo alvarius) also known as the Sonoran Desert toad, is a toad species found in northwestern Mexico and the southwestern United States. It is well known for its ability to exude toxins from glands within its skin that have psychoactive properties.
The toad's scientific name used to be Bufo alvarius, the name for which the toad is generally colloquially still known as. In the early 2000s, the increasingly important role of molecular genetic techniques in taxonomy and their ability to examine phylogenetic relationships allowed scientists to discover numerous distinct genera within the old Bufo group.
The Colorado River toad's name was subsequently changed to Incilius alvarius. The Colorado River toad can grow to about 190 millimetres (7.5 in) long and is the largest toad in the United States apart from the non-native cane toad (Rhinella marina). It has a smooth, leathery skin and is olive green or mottled brown in color. Just behind the large golden eye with a horizontal pupil is a bulging kidney-shaped parotoid gland. Below this is a large circular pale green area which is the tympanum or ear drum. By the corner... Wikipedia →
Recording0:32
United States · 2025
© C. Mallory · iNaturalist · CC BY-NC 4.0
Recording0:10
United States · 2023
© Emilio Romero · iNaturalist · CC BY-NC 4.0
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United States · 2025
© Logan Young · iNaturalist · CC BY-NC 4.0
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Saguaro National Park | 🇺🇸 United States |
More parks will be added in future updates.
| # | Zoo / Centre | Country | |
|---|---|---|---|
| 1 | San Diego Zoo | 🇺🇸 United States | |
| 2 | Pairi Daiza | 🇧🇪 Belgium | |
| 3 | Prague Zoo | 🇨🇿 Czechia | |
| 4 | Leipzig Zoological Garden | 🇩🇪 Germany | |
| 5 | Zürich Zoo | 🇨🇭 Switzerland | |
| 6 | North Carolina Zoo | 🇺🇸 United States | |
| 7 | Living Desert Zoo and Gardens | 🇺🇸 United States | |
| 8 | Sedgwick County Zoo | 🇺🇸 United States | |
| 9 | Oakland Zoo | 🇺🇸 United States | |
| 10 | Phoenix Zoo | 🇺🇸 United States | |
| 11 | Toledo Zoo | 🇺🇸 United States | |
| 12 | Louisville Zoo | 🇺🇸 United States | |
| 13 | Yaroslavl Zoo | 🇷🇺 Russia | |
| 14 | ABQ BioPark: Zoo, Aquarium, Botanic Garden | 🇺🇸 United States | |
| 15 | Burgers' Ocean | 🇳🇱 Netherlands | |
| 16 | Berlin Zoological Garden | 🇩🇪 Germany | |
| 17 | Royal Burgers' Zoo | 🇳🇱 Netherlands | |
| 18 | Wrocław Zoological Garden | 🇵🇱 Poland | |
| 19 | Zoologischer Garten Leipzig | 🇩🇪 Germany | |
| 20 | Indianapolis Zoo | 🇺🇸 United States | |
| 21 | Arizona-Sonora Desert Museum | 🇺🇸 United States | |
| 22 | Philadelphia Zoo | 🇺🇸 United States | |
| 23 | Schönbrunn Zoo | 🇦🇹 Austria | |
| 24 | Hogle Zoo | 🇺🇸 United States | |
| 25 | Łódź Zoo | 🇵🇱 Poland | |
| 26 | Tierpark Bern | 🇨🇭 Switzerland | |
| 27 | Little Rock Zoo | 🇺🇸 United States | |
| 28 | Zoo Neuwied | 🇩🇪 Germany | |
| 29 | Frankfurt Zoological Garden | 🇩🇪 Germany | |
| 30 | Leningrad Zoo | 🇷🇺 Russia | |
| 31 | Alligator Adventure | 🇺🇸 United States | |
| 32 | Peoria Zoo | 🇺🇸 United States | |
| 33 | Elmwood Park Zoo | 🇺🇸 United States | |
| 34 | Downtown Aquarium, Denver | 🇺🇸 United States | |
| 35 | Africarium | 🇵🇱 Poland | |
| 36 | Oceanium | 🇳🇱 Netherlands | |
| 37 | OdySea Aquarium | 🇺🇸 United States | |
| 38 | Haus des Meeres | 🇦🇹 Austria | |
| 39 | Aquarium Berlin | 🇩🇪 Germany | |
| 40 | Children's Aquarium at Fair Park | 🇺🇸 United States | |
| 41 | Rákosův pavilon | 🇨🇿 Czechia | |
| 42 | Velemlokárium | 🇨🇿 Czechia | |
| 43 | Chehaw Park | 🇺🇸 United States | |
| 44 | Kung Fu Corals | 🇺🇸 United States | |
| 45 | terrarium ogrodu zoologicznego we Wrocławiu | 🇵🇱 Poland | |
| 46 | Wolfgang-Köhler-Primaten-Forschungszentrum | 🇩🇪 Germany |
With luck
About 10% of wildlife watchers report a Colorado River Toad sighting in Phoenix on a given day, based on 23 verified sightings from GBIF citizen-science data. It is the 4th most-seen of the 6 amphibians we can rate there. Over three days the chance rises to about 20%, and over a week to about 40%, if each day is a fresh chance.
June to November
In those months about 10% of wildlife watchers report a Colorado River Toad in Phoenix on a given day, against under 5% in December to May, the lowest months.
Between 7 and 10 pm
Across all the parks we cover, that three-hour window holds the most Colorado River Toad sightings with a recorded time, and about 8 in 10 of them come between 6 pm and 6 am: it is mostly seen at night.
Among the best
Of the 2 cities where we can rate Colorado River Toad sightings, Phoenix ranks 2nd at about 10%, level with the leaders once rounded. The best odds are in Mesa (United States, about 10%).
GBIF citizen-science records
It is estimated from how often the Colorado River Toad is recorded against all the amphibians logged in Phoenix (23 verified sightings), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
